Regenerative braking is known in the art for various vehicles such as, for example, hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). During a regenerative braking event, an electric motor/generator converts rotational kinetic energy into electric energy that can be stored in a high voltage traction battery. Friction braking is also typically available in vehicles that are equipped with regenerative braking. A hydraulic braking system is known as one form of activating friction braking, in which pressurized brake fluid is transferred to the wheel brakes to apply friction to the wheels. A vacuum booster may also be provided in hydraulic braking systems to assist the translation of pedal movement into
Circumstances may dictate that friction braking is utilized instead of regenerative braking. For example, if the state of charge in the high voltage traction battery is relatively high, vehicle controllers may disable regenerative braking and instead command friction braking in response to an operator of the vehicle depressing the brake pedal.
During a braking event, it may be beneficial to command regenerative braking only without hydraulic braking assist during initial movement of the brake pedal. For example, in U.S. Pat. No. 7,232,192 teaches a known deadband displacement range defined as a disconnection between connecting rods that connect the brake pedal to the hydraulic braking system. Brake pedal movement within the deadband displacement range results in activation of regenerative braking without activation of friction braking. While the deadband displacement range in a braking system is known in the art, it may not desirable in all vehicles.